Police Blotter is a weekly News.com report on the intersection of technology and the law.

What: Minnesota man charged with alien smuggling says data from a location tap of his T-Mobile phone should not be used against him in court.

When: U.S. District Judge Paul Magnuson in Minnesota rules on January 31.

Outcome: Prosecutors can use location information.

What happened, according to court documents: Federal prosecutors have been arguing that they should be able to track the locations of Americans through their cell phones without showing any evidence of criminal activity--in legalese, no "probable cause"--because cell-tracking technology is not that precise. Police Blotter was the first to report on this trend nearly three years ago.

In one case in Texas, for instance, prosecutors claimed in a legal brief (PDF) that: "It is true that cell-site data provides information about the location of a cell phone user. However, cell phones do not permit the detailed continuous tracking of movement..."

That was then. Now that the Federal Communications Commission's E911 requirements have led to the adoption of assisted GPS and triangulation through cellular towers, "detailed continuous tracking of movement" has become commonplace. (The Sprint Navigation and Verizon's VZ Navigator feature are two examples.)

This bring us to a case where Homeland Security's Immigration and Customs Enforcement (ICE) obtained latitude and longitude data from T-Mobile showing the location of one of the company's subscribers. ICE obtained a court order in October from a magistrate judge requiring T-Mobile to disclose the location "at such intervals and times as directed by the law enforcement agent serving this order," which would include a real-time feed as the subscriber is traveling.

To comply with E911, T-Mobile uses a GSM technology called Uplink Time Difference of Arrival, or U-TDOA, which calculates a position based on precisely how long it takes signals to reach towers. A company called TruePosition that provides U-TDOA services to T-Mobile boasts of "accuracy to under 50 meters" that's available "for start-of-call, midcall, or when idle." The company also says: "U-TDOA systems typically deliver locations to the network in less than 10 seconds from the initiation of the call, often before the voice conversation even begins."

When Wu found out location information would be used against him in court, he objected to it, saying the court order was granted based on the unconfirmed claims of informants and the location data therefore should be suppressed. A brief he filed in November said: "The affidavit submitted in support of the application for the order is largely based upon information supplied by two anonymous informants--CRI and CW. However, the affidavit fails to adequately establish the credibility and reliability of the two informants. The substance of the affidavit is really little more than a repetition of the largely uncorroborated assertions of CRI and CW."

So far he's had little luck with that argument. U.S. District Judge Paul Magnuson in Minnesota rejected the suppression request on January 31, saying there was "ample evidence" the order was reasonable. Magnuson also denied suppression requests for e-mail evidence obtained from Wu's Yahoo, Hotmail, and Gmail accounts.

In this case, police did prove they had a reasonable belief that a crime had been committed--again, probable cause--and obtained a court order signed by a judge. That means the privacy concerns in this case were not as severe as some of the earlier ones.

What's worth watching is whether the Justice Department tries to obtain similar location tracking by-the-minute-and-by-the-meter data in the future without demonstrating probable cause first. Notes Marc Rotenberg of the Electronic Privacy Information Center: "From the privacy perspective, you're going for two things, judicial review and an appropriately high standard."

Excerpt from October 25, 2007, court order to T-Mobile, which was originally sealed:
T-Mobile shall disclose at such intervals and times as directed by ICE, latitude and longitude data that establishes the approximate positions of the Subject Wireless Telephone, by unobtrusively initiating a signal on its network that will enable it to determine the locations of the Subject Wireless Telephone...

It is further ordered that pursuant to the same authority that T-Mobile shall initiate a signal to determine the location of the subject's mobile device on the service provider's network or with such other reference points as may be reasonable (sic) available and at such intervals and times as directed by the law enforcement agent serving this order...

It is further ordered, pursuant to the All Writs Act, 28 USC 1651(a), that T-Mobile shall be paid compensation by ICE for reasonable expenses directly incurred in providing the facilities and assistance described above...

It is further ordered pursuant to the All Writs Act, 28 USC 1651(a), that T-Mobile, its representatives, agents, and employee(s), unless and until otherwise ordered by the court, shall not disclose in any manner, directly or indirectly, by any action or inaction, the existence of this order...

Excerpt from January 31 court opinion by Judge Magnuson saying the T-Mobile tracking was perfectly reasonable:
Turning next to the application for the latitude/longitude order, this probable cause is based largely upon information gathered by the agents after consensually monitored calls by the CRI and CW. During the calls, Wu discussed the scheme and made identical statements to the CW and CRI. The phone numbers were interconnected and it was clear they were used for the purpose of communicating about the scheme. There is more than ample evidence in this affidavit for the request given the information gathered within control of the agents, in combination with the common facts listed earlier. They are mutually confirming facts and it all points toward probable cause.

If you track my phone it will give you no inclination as to where I am whatsoever. I forget it in the car or at work weekly. Other times I don?t even take it to work. Most of the time when I leave with my wife she takes hers, and I won?t take mine.

Also, I don?t like to be bothered while driving. When I am driving it is off. If you can track mine when it is off or not I don?t know, but when I am in the car it is off.

I just don?t like to be reachable 24/7 like other people, and I generally hate telephones anyway. I like text messages or email. Send me a message, and I can deal with it when I feel like it instead of when you feel like it. It is also off while I am sleeping.

If there is an emergency you should be calling 911, not me. They aren?t going to let me into surgery anyway. You can text me directions and the hospital?s visiting hours. Is there a nuclear attack? I can?t outrun a nuclear bomb! Stop wasting my time! I?m sleeping.

My boss gets mad at me because I don?t leave it on 24/7. However, he doesn?t pay me 24/7 so I don?t see the problem.

When I don?t mind being bothered I?ll take it, but if I?m going out with friends or whatever it stays home, and they get my full attention. Other people will have to leave a message.

I would say me and my phone are only on the same side of town about 50% of the time.

From the day this requirement was added using emergency calls as an excuse, it was evident the main use for it was to track people. For the majority of people who always carry them around, it allows their geolocation data to be stored indefinitely, minute by minute. If carefully compressed, the data with 1 minute resolution is only 526K readings / year. With differential coding and a bit of compression 50 years of every place a person have ever been (with his cell phone) can fit in a quarter of a CD, or about 20 cents worth of disk space making it financially possible.

Coupled with the ability to activate the mic remotely, we end up voluntarily carrying a powerful and hostile spying device.

Unfortunately, people simply seem to get used to this permanent spying and still think we're free, unable to see the essence of freedom being taken away from them.

T-MOBILE SUCK NO PRIVET SEE.TRACKING CELL PHONES IF T-MOBILE KEEP THIS UP THERE GOIN TO GO OUT OF BISSNESS I NOW. WY IM GOIN TO ANOTHER CELL PHONE COMPANY. INVATION OF PRIVETSEE .THERE GOES ARE FREEDOME OF SPEECH.WITH T-MOBILE YOU GOT NO FREEDOME OF SPEECH...........SO IF YOU HAVE T-MOBILE WATCH OUT THEY NO WHERE YOU ARE.SO HAVE T-MOBILE YOU HAVE NO FREEDOME OF SPEECH THATS WHAT THERE TELLING US.THAT ONLY THING THAT SHOUD NO YOU AT IS GOD.NOW DO YOU WANT SOME BODY PLAYING GOD,T-MOBILE DOES.GOIN OUT BISSNES IF THEY KEEP DOIN THIS. THIS IS AMERICA JACK.FREEDOME OF SPEECH RULES.AND TO T-MOBILE INC.DONT TAKE ALWAY MY FREEDOME OF SPEECH

T-MOBILE SUCK NO PRIVET SEE.TRACKING CELL PHONES IF T-MOBILE KEEP THIS UP THERE GOIN TO GO OUT OF BISSNESS I NO. WY IM GOIN TO ANOTHER CELL PHONE COMPANY. INVATION OF PRIVETSEE .THERE GOES ARE FREEDOME OF SPEECH.WITH T-MOBILE YOU GOT NO FREEDOME OF SPEECH...........SO IF YOU HAVE T-MOBILE WATCH OUT THEY NO WHERE YOU ARE.SO HAVE T-MOBILE YOU HAVE NO FREEDOME OF SPEECH THATS WHAT THERE TELLING US.THAT ONLY THING THAT SHOUD NO YOU AT IS GOD.NOW DO YOU WANT SOME BODY PLAYING GOD,T-MOBILE DOES.GOIN OUT BISSNES IF THEY KEEP DOIN THIS. THIS IS AMERICA JACK.FREEDOME OF SPEECH RULES.AND TO T-MOBILE INC.DONT TAKE ALWAY MY FREEDOME OF SPEECH

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